1. Field:
The invention is in the field of dentistry and has to do with the anchoring of overdentures and partial dentures to tooth roots that remain after removal therefrom of the normally associated natural teeth.
2. State of the Art:
A variety of systems have been developed heretofore and are in more or less satisfactory use for removably retaining so-called "overdentures" and partial dentures in the mouth by anchoring them to one or more tooth roots remaining after removal of the teeth therefrom down to the vicinity of the gum line.
In several of these prior art systems, a female member of at least one pair of anchor members is placed in the natural tooth root and root canal as prepared to receive the same and is firmly secured therein, as by cementing. Such female member is usually made of stainless steel. Various types of male members are used depending upon the particular system.
In one of the prior art systems, the male member of a pair of anchor members is a post of nylon plastic having a ball-shaped head for snapping into the female member to provide resiliency, rotational freedom, and ease of placement of the denture in and removal from the mouth of the dental patient. The base of such male member is firmly embedded in the material of the denture, which is allowed to cure about such base of the male member. A centering sleeve is normally placed on the exposed shank of the male member during the embedding procedure as an aid to maintaining proper mating interengaging placement of the male and female pair of anchor members.
A problem associated with this otherwise very effective and convenient system is the fact that the ball-headed male member is subject to wear and must be replaced frequently. This involves excavation of the denture material, usually an acrylic plastic, surrounding the base of the male member, insertion of the base of a replacement male member in the excavation, and the placement of fresh denture material in the excavation surrounding the base of the new male member so as to firmly secure such new male member in place upon setting up of the newly placed denture material.